Dear EarthTalk: There are a number of companies out there now doing "energy audits" for the home, after which they try to sell you attic insulation and other products and services. Is this just a scam or would it be wise for me to look into this? -- Bill Richards., New York, N.Y.

For the most part, companies offering energy audits are reputable and legitimate and will help you both save money and reduce your carbon footprint if you follow their advice in regard to upgrading things like insulation, windows and appliances.

"A home energy assessment, also known as a home energy audit, is the first step to assess how much energy your home consumes and to evaluate what measures you can take to make your home more energy efficient," reported the U.S. Department of Energy (DOE). "An assessment will show you problems that may, when corrected, save you significant amounts of money over time."

"During the assessment, you can pinpoint where your house is losing energy," added DOE. "Energy assessments also determine the efficiency of your home's heating and cooling systems [and] may also show you ways to conserve hot water and electricity."

You can conduct your own energy audit if you know where to look for air leaks (drafts), water waste and other key areas of a home's inefficiencies. The DOE's energysavers.gov website has guidelines to help homeowners conduct their own do-it-yourself home energy assessments. For instance, DOE recommends that homeowners make a list of obvious air leaks, such as through gaps along baseboards or at the edges of flooring and at wall and ceiling junctures. The potential energy savings from reducing drafts in a home can be as high as 30 percent per year, reported DOE. (The DOE website also provides information on other ways to save money and resources through less obvious things such as outdoor landscaping. It also posts guidelines for energy-efficient designing and remodeling.)

You should also check the filters on heating and cooling equipment to see if they need to be changed so as to keep your furnace and air conditioners functioning at maximum efficiency. And if these or other appliances over 15 years old consider replacing them with newer models that meet federal EnergyStar efficiency criteria. Also, swapping out older incandescent bulbs in light fixtures with higher efficiency compact fluorescent or LED bulbs will save money and energy.

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A professional energy auditor with dedicated assessment tools and the knowledge of how to use them will in all likelihood carry out a more comprehensive assessment than you can do yourself. Thorough assessments often use equipment such as blower doors, which measure the extent of leaks in the building envelope, and infrared cameras, which reveal hard-to-detect areas of air infiltration and missing insulation.

If you are concerned about enlisting a for-profit firm that upsells its own energy efficiency upgrade services based on a "free" energy audit, check with your utility to see whether it offers unbiased, independent energy audit services (which it may do for free or for a nominal cost). The assessor from your utility may be able to recommend window and door replacement companies, heating and cooling specialists and other vendors nearby that do reputable work to make your home is not only energy efficient but warmer in the winter and cooler in the summer.

Contacts: DOE Energy Savers, www.energysavers.gov; EnergyStar, www.energystar.gov.

Dear EarthTalk: What's the story with Echinacea? Many herb teas contain it, and many people swear by it as a cold remedy. But I've also seen headlines saying that the herb has no medicinal value whatsoever. Can you set the record straight? -- Arlene Hixson, Portland, Maine

Echinacea, also known as purple coneflower, has gained popularity in recent years as a nutritional supplement that proponents believe is helpful in staving off the common cold and shortening its duration. But given the variation between dosages and formulations -- such herbs are not regulated as medical drugs by the U.S Food and Drug Administration (FDA) and so makers have little incentive to standardize -- it's hard to get definitive answers as to Echinacea's effectiveness.

Historically, Native Americans relied on the root of Echinacea to numb toothache pain and treat dyspepsia as well as snake, insect and spider bites. While some modern day folks rely on Echinacea just based on this anecdotal evidence, scientific studies have verified that the herb can be effective. To wit, a 2008 University of Connecticut review of 14 different clinical trials of Echinacea use found that taking the supplement reduced the chances of getting a cold by 31 percent, and helped people get over cold and flu symptoms a day and a half earlier than those who didn't take it.

Researchers initially thought Echinacea's effectiveness was due to its immune-boosting traits, but they now believe instead that the herb works more as an anti-inflammatory agent. A 2009 University of British Columbia study found that typical commercially available Echinacea preparations are effective in reducing the body's production of inflammatory proteins in human bronchial cells. In layman's terms, this means that Echinacea can help lessen the annoying symptoms of common colds, the flu and other respiratory ailments. Furthermore, the study found that Echinacea is just as effective in reducing bronchial inflammation whether it is consumed before or after a viral infection sets in, indicating that taking moderate doses on a regular basis during cold season can help prevent some bronchial irritation if and when cold symptoms begin.

Interestingly, though, a 2010 study of 719 participants in Wisconsin focusing on illness duration and severity found that the duration of the common cold could be shortened by taking a pill of some sort, whether Echinacea or a placebo with no active ingredients. But this study merely underscored the importance of psychological factors in fighting illness and did not say that Echinacea isn't effective.

Given the lack of FDA oversight of herbs, different formulations may contain vastly different amounts of Echinacea. A 2004 evaluation of 19 different Echinacea brands by the non-profit Consumers Union and published in Consumer Reports found that the amount of Echinacea actually present in supplements varied considerably from brand to brand -- and even in some cases from bottle to bottle of the same brand. The magazine recommended a few brands as "best picks," including Spring Valley, Origin and Sundown, all which featured high concentrations of Echinacea and reliable dosage amounts from pill to pill.

Before taking the Echinacea plunge, beware that the herb can cause allergic reactions in some people and may interact negatively with some common medications. Researchers warn that anyone with autoimmune disease or a handful of other illnesses should not take Echinacea without first consulting with their doctor.

Contacts: FDA, www.fda.gov; Consumers Union, www.consumersunion.org.

EarthTalk is written and edited by Roddy Scheer and Doug Moss and is a registered trademark of E -- The Environmental Magazine (www.emagazine.com). Send questions to: earthtalk@emagazine.com. Subscribe: www.emagazine.com/subscribe. Free trial issue: www.emagazine.com/trial.